Im wondering if anyone knows if there is a minimum lead time to book the GMAT. For example, if you wanted to, could you book the test tomorrow, or do you need to give at least a week?
Nope, you don't need any lead time really. A day is enough... assuming:
The main restriction on taking the GMAT is available slots at the testing center committed for the GMAT (the testing centers offer many other tests).
For my first attempt, I kept my eye on one date and kept checking availability. About a week before said date, a spot opened up and I booked the slot.
For my second attempt, I reserved the spot about two months ahead of time.
That being said:
I would advise against booking the test with one day of lead time. The test requires some mental prep and motivation (proper sleep, a bit of relaxation before the test, prepping for things to take with you (water/snacks), etc.), and you might become a bit panic stricken if you have less than 24 hours to address the day of the test.
Speaking of things you can take with you, what are you allowed to take with you? I was under the impression I can't bring and water or snacks..